1. Field of the Invention
The present invention relates to an inkjet printer and an ink dryer for the inkjet printer.
2. Discussion of the Background
In an inkjet printer, printing is conducted by ejecting dye-type ink such as acid dye, reactive dye, and substantive dye or pigment-type ink containing organic solvent such as solvent ink, onto a surface or both front and back surfaces of a sheet-like medium (recording medium) made of paper, silk, cotton, vinyl chloride, or the like. Especially in the industrial field, in such an inkjet printer, it is important to effectively dry a medium after deposition of ink onto the medium in order to quickly and easily conduct shipment and delivery after printing.
For example, JP-A-2003-22890 discloses a drying apparatus for drying ink on a medium. The drying apparatus includes a wave guide having a slot, which is configured to allow the medium to move through the slot, and an electromagnetic energy source, which is adapted to establish an electric field within the wave guide such that an angle formed between a direction of the electric field and a longitudinal axis of fibers of the medium becomes greater than ten degrees and less than or equal to ninety degrees. The drying apparatus disclosed in JP-A-2003-22890 has a wave guide choke attached to the slot in order to reduce disruption in wall currents caused in the wave guide due to the slot.
However, in the technology of allowing a medium to move through the wave guide and supplying electromagnetic waves into the wave guide so as to dry the medium, the electromagnetic waves inside the wave guide have a tendency to leak out of the wave guide along the front and back surfaces of the medium moving through the wave guide. Accordingly, since a shielding means is required to prevent the electromagnetic waves from leaking out of the wave guide, the technology has a problem of little practicability.
On the other hand, there is another method of using an electrothermal heater or the like for drying the medium. However, the electrothermal heater or the like has a problem of extremely large power consumption. Though a method of improving the drying speed of ink is also conceivable, the improvement in drying speed of ink nearly reaches the limit so that it is difficult to further speed up the drying of the media in inkjet printers only by improvement in drying speed of ink.